There is an easy (and quite illicit) way to up your health rating. Carjack a fairly decent ride and cruise into the Red Light District. Pull up next to one of the hookers and stop. She'll talk to you and if she likes your ride, she'll get inside. The moment she gets in, your money will gradually decrease. Drive her to a deserted alley and let the car sit. Eventually, the car will begin to rock, first slowly, then faster. Your health will increase as the vehicle shakes. Who knows what's going on inside? In the end, your health will grow to 125, and will last until the next time you croak.